People show a willingness to pay more for the benefits and costs associated with having trees on the property. National studies have shown properties along tree-lined streets may be up to 6% higher value than without. (1 – see numbered citations below) Developers in Hawaii claim to receive higher prices for property with trees.2

Total annual benefit of trees on property values in Honolulu: $3.16 Mil*

Trees Are Good for Business

People across the country have shown higher affinity towards retail locations with trees and they will spend more time and more money (9-12% more) while shopping there. (3)

They also improve water quality by reducing soil erosion and removing pollutants (5)

Trees in Honolulu intercept 35 mil. gal of stormwater/ year. This contribution is valued at $350,104/yr (this is a conservative estimate) (3)

Tree provide Social Benefits

Trees improve quality of life in many psychological and social ways. Trees play an important role in reducing stress, promoting physical and mental well-being and in general contribute to healthier communities.

Trees Help Reduce Stress and Improve Overall Well-being

Studies have found that nature viewing after stressful situations results in reduced physiological stress response and more positive emotional responses. In addition, walking in nature or viewing pictures of nature can improve directed-attention abilities.

Trees Reduce Driver Stress

Placing trees next to freeways and roads, and having roads pass through and by green areas, reduces driver stress as measured by blood pressure, heart rate and sympathetic nervous system changes.(8)

Trees Improve Learning & Concentration in Schools

Although not specifically referencing trees, a study at the University of Hawaii showed:

Students scored higher on standardized testing, and had less disciplinary problems when plants were present in classrooms.

Students reported that they had lower levels of stress, felt more comfortable, felt the air was fresher, and were able to concentrate for longer periods. (9)

Image by Heidi Bornhorst

Girls with greener views from home were shown to have greater self- discipline, were less impulsive and had better concentration. This in turn led to better life decisions and better school performance. (These findings applied only to girls; boys are apparently farther ranging, spending more time farther from home than girls.) (11)

Children who played in more natural play areas displayed substantially fewer problems of attention. (12)

Trees Make Communities More Livable

Trees encourage people to spend more time outside interacting with other people in their communities. Trees that provide shade are gathering places and increase the use of outdoor common spaces.(13)

Trees Lead to Reduced Crime

All other factors being similar, areas with more landscaping and trees show less crime. It is thought this is due to the increased surveillance from people being drawn outside and the calming effects of trees.

Views of nature have led to 23% fewer sick days among workers and overall improved well-being. It also results in higher productivity and satisfaction for workers. (16, 17)

Research has shown, exposure to nature and gardens speeds recovery of hospital patients and results in fewer complications and a more positive outlook among patients post-surgery. Most (80% as evaluated by a Johns Hopkins Medical School evaluation) rigorous studies found positive links between environmental characteristics and patient health outcomes. (18, 19, 20)

(1) Wolf, K, 1998. Urban Forest Values: Economic Benefits of Trees in Cities, University of Washington College of Forest Resources, Factsheet #29.(2) Alan Arakawa, Castle and Cook, “Design, Construction and Maintenance with Trees in Mind” conference, Honolulu, October 2005.(3) STRATUM: Vargas, K. E., McPherson, G. E., Simpson, J. R., P. J. Peper, Gardner, S.L., Xiao, Q.City of Honolulu, Hawaii Municipal Forest Resource Analysis. Center for Urban Forest Research, USDA Forest Service, Pacific Southwest Research Station. November, 2007. Note about data and methodology: “The estimates in the Stratum provide first-order approximations of tree value. … This estimate of benefits applies only to the 43,817 trees in the inventory. Unfortunately, because the inventory does not represent a statistically random sample of the population, it is not possible to extrapolate directly from the values given here for the inventoried trees to the urban forest as a whole. It is clear, however, that the total benefits are at least several times those given here.” For Complete description of methodology and procedures see Appendix D, p.51(4) Wolf, Kathleen L. “More In Store: Research on City Trees and Retail.” Arborist News, Vol. 18, No. 2, April 2009, 22-27.(5) Fazio, J.R., Ed. “How Trees Can Retain Stormwater Runoff” Tree City USA Bulletin No 55. Arbor Day Foundation:http://www.fs.fed.us/psw/programs/uesd/uep/products/11/800TreeCityUSABulletin_55.pdf(6) Hastie, C. 2003. “The Benefits of Urban Trees”(7) Bornhorst, Heidi. “Threatened tern an appropriate choice as city bird,” Honolulu Advertiser. April 20, 2007.